3-Methoxy-1-propanol is used as a synthesis building block for preparing pharmaceutically active compounds. It can be employed, for example, in the synthesis of a stomach therapeutic (see EP-A 268,956).
Various methods for preparing 3-methoxy-1-propanol are known. However, all of them have disadvantages. Can. J. Chem. 42, 2113 (1964), for instance, describes the preparation of 3-methoxy-1-propanol from 3-chloro-1-propanol using sodium methoxide in methanol. According to this process, sodium methoxide is initially charged in methanol and 3-chloro-1-propanol is added at boiling point. The yield of 3-methoxy-1-propanol is only 21%. JP Published Specification 08-113546 likewise describes the methoxylation of 3-chloro-1-propanol with sodium methoxide. A yield of 69.8% is said to have been obtained, a result which is still unsatisfactory.
For the reaction of 3-bromo-1-propanol with sodium methoxide, only a yield of 20% is described (see Helv. Chim. Acta 63, 2152 (1980)).
Can. J. Chem. 63, 1833 (1985) describes the formation of 3-methoxy-1-propanol from sodium 3-hydroxypropylate with methyl iodide, J. Amer. Chem. Soc. 65, 1276 (1943). A disadvantage of this process is the fact that expensive methyl iodide is used as a reagent and that a yield of only 64% is obtained.
Furthermore, it is known to prepare 3-methoxy-1-propanol by reaction of 3-methoxypropionaldehyde (see DE 579,651 and Can. J. Chem. 63, 1833 (1985)), by hydration of 3-methoxypropene with mercury acetate and sodium borohydride (see J. Org. Chem. 46, 531 (1981)), by ring-opening of 1,3-dioxane with boron halides (see J. Chem. Soc. Perkin. Trans. I, 1807 (1981)) and by basic or acidic ring opening of oxetane with methanol (see J. Amer. Chem. Soc. 76, 56 (1954)). Disadvantages of these methods are the use of expensive reagents, low yields and the toxic salts which are formed in some cases. These processes are also uneconomical, and some of them require particular ecological expenses.
It is therefore an object of the present invention to provide an economically and ecologically favorable process for preparing 3-methoxy-1-propanol which uses readily available and inexpensive starting materials and provides good yields of desired product.